The present invention is directed to zig-zag picket type graphite heater elements for use in crystal growing furnaces and the like, and particularly to heaters wherein a plurality of like graphite cylindrical shell segments are connected in circumferentially separated position, but cylindrical formation, by graphite connector elements, certain of which also function to couple the electrical current source to the heater. The present application is directed to improvements in heater systems of the type disclosed in the present applicant's application Ser. No. 522,727, filed Aug. 12, 1983, now U.S. Pat. No. 4,549,345, which is a division of Ser. No. 323,122, filed Nov. 19, 1981, now U.S. Pat. No. 4,410,796.